On the Settings->"Preferences", "Tab Settings" tab, I set "[Default]" at Tab size: 8, uncheck Replace by space; and set "Python" to uncheck Use default value, Tab size: 4, check Replace by space. This causes inserts into a python source to use 4 spaces for indents, and indent with spaces instead of tabs.
If I end up with any tabs in the source, I use Edit->Blank Operations->TAB to Space to convert them. I also clean up trailing blanks with Edit->Blank Operations->Trim Trailing Space.
I install and use the pep8 package to verify standard formatting.http://www.reddit.com/r/Python/comments/2mfrn6/python_in_notepad/cm3tdj5